Similar to avolites playback-groups, I wish there was a group for submasters/faders.
The way I imagine this to work would be that you add subs/faders to the list and only one item in the list can be active at a time.
All others get released.
This could of course be expanded with different options. A group master of sorts would be handy.
There could also be different settings for when a new group-item takes over.
